package com.wk.util;

import java.io.IOException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class DESEncryption {
	
	 private final static String DES = "DES";
	
	 private final static String MOBILE_ATTENDANCE_KEY = "5tJByL2Hkt7rABzCdMkEn5YXfxG81IjK";
	 
	 public static void main(String[] args) throws Exception {
	        String data = "123456";
	        String key = "admin";
	        System.err.println(encrypt(data, key));
	        System.err.println(decrypt(encrypt(data, key), key));
	 
	    }

		/**
		 * 根据默认键值进行加密
		 * @param data
		 * @return
		 * @throws Exception
		 */
	    public static String encrypt(String data) throws Exception{
	    	return encrypt(data,MOBILE_ATTENDANCE_KEY);
	    }
	    /**
	     * Description 根据键值进行加密
	     * @param data 
	     * @param key  加密键byte数组
	     * @return
	     * @throws Exception
	     */
	    public static String encrypt(String data, String key) throws Exception {
	    	String entryKey = getEncryKey(key);
	        byte[] bt = encrypt(data.getBytes(), entryKey.getBytes());
	        String strs = new BASE64Encoder().encode(bt);
	        return strs;
	    }
	 
	    /**
	     * Description 根据键值进行解密
	     * @param data
	     * @param key  加密键byte数组
	     * @return
	     * @throws IOException
	     * @throws Exception
	     */
	    public static String decrypt(String data, String key) throws IOException,
	            Exception {
	        if (data == null)
	            return null;
	        String entryKey = getEncryKey(key);
	        BASE64Decoder decoder = new BASE64Decoder();	        
	        byte[] buf = decoder.decodeBuffer(data);
	        byte[] bt = decrypt(buf,entryKey.getBytes());
	        return new String(bt);
	    }
	 
	    /**
	     * Description 根据键值进行加密
	     * @param data
	     * @param key  加密键byte数组
	     * @return
	     * @throws Exception
	     */
	    private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
	        // 生成一个可信任的随机数源
	        SecureRandom sr = new SecureRandom();
	 
	        // 从原始密钥数据创建DESKeySpec对象
	        DESKeySpec dks = new DESKeySpec(key);
	 
	        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
	        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
	        SecretKey securekey = keyFactory.generateSecret(dks);
	 
	        // Cipher对象实际完成加密操作
	        Cipher cipher = Cipher.getInstance(DES);
	 
	        // 用密钥初始化Cipher对象
	        cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
	 
	        return cipher.doFinal(data);
	    }
	     
	     
	    /**
	     * Description 根据键值进行解密
	     * @param data
	     * @param key  加密键byte数组
	     * @return
	     * @throws Exception
	     */
	    private static byte[] decrypt(byte[] data, byte[] key) throws Exception {
	        // 生成一个可信任的随机数源
	        SecureRandom sr = new SecureRandom();
	 
	        // 从原始密钥数据创建DESKeySpec对象
	        DESKeySpec dks = new DESKeySpec(key);
	 
	        // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
	        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
	        SecretKey securekey = keyFactory.generateSecret(dks);
	 
	        // Cipher对象实际完成解密操作
	        Cipher cipher = Cipher.getInstance(DES);
	 
	        // 用密钥初始化Cipher对象
	        cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
	 
	        return cipher.doFinal(data);
	    }
	    
	   private static String getEncryKey(String key){
		   String encryptKey = key;
			int enkeyLen = 8;
			int keyLen = key.length();
			
			if(keyLen > enkeyLen){
				encryptKey = encryptKey.substring(0,8);	
			}else{
				int paddLen = enkeyLen - keyLen;
				for(int i=0;i<paddLen;i++){
					encryptKey += "0";
				}
			}
			return 	encryptKey;
	   }

}
